Classification Flashcards
(32 cards)
What is biodiversity?
Measure of variety of living organisms and their genetic differences.
What are the rules of the binomial system for classification?
- italics
- genus name has upper-case letter, species name has lower-case e.g. Homo sapiens
- after first use, they’re abbreviated to initial of genus and then species name eg H. sapiens
What are the domains?
Archaea, Bacteria, Eukaryota
What does the Archaea domain contain?
Archaebacteria: ancient bacteria thought to be early relatives of eukaryotes, extremophiles included!! asexual
What does the bacteria domain contain?
Eubacteria: true bacteria, cyanobacteria. asexual
What does the eukaryota domain contain?
Protoctista: microscopic organisms. Some are heterotrophs, some autotrophs.
Fungi: all heterotrophs, mostly live on dead things. They ahve chitin in their cell walls.
Plantae: almost all autotrophs, making food using psynthesis.
Animalia: heterotrophs that move their whole bodies during at least one stage of life cycle. Invertebrates, and vertebrates.
What are all the main taxonomic groupings?
Domain, kingdom, phylum/division, class, order, family, genus, species. DK Police Department can’t offer feds government secrets.
What was the morphological species concept and why didn’t it work?
Based on categorizing using appearance of organisms. But appearance of organism can be affected by many things and there can be lots of variation within a group of closely related organisms. Also sexual dimorphism (female/male differences)
What was the original reproductive concept for classification? What was wrong with it?
A group of organisms with similar characteristics that interbreed to produce fertile offspring.
But not all of the organisms in a species can interbreed because they don’t all live in the same area. Also in some cases, different species can sometimes reproduce to give fertile offspring.
What are the two revised new reproductive concepts for classification?
- group of organisms with similar characteristics that are all potentially capable of breeding to produce fertile offspring
- group of organisms in which genes can flow between individuals
What’s a weakness in the new revised reproductive concept for classification?
Doesn’t help to classify plants because they frequently interbreed with similar species to form fertile offspring.
What is the ecological species model and why is it weak?
based on ecological niche occupied by an organism. Niche definitions vary and many species occupy more than one niche.
Why is the original reproductive concept good?
Overcomes issues like sexual dimorphism and is a good working definition for many animal species.
What is the mate-recognition species model and why is it weak?
Based on unique fertilisation systems like mating behaviour. But many species will mate or cross-pollinate other species and may even produce fertile offspring but are still different species.
why is classification important? (4)
- One organism will have different names in different countries/areas - we need to be sure we’re referring to the same organism.
- Biodiversity is very important, but to quantify it we need to identify different groups of organisms.
- Helps scientists monitor how populations change.
- Helps biologists understand how different types of living organisms are related.
What is the genetic species model and why is it weak (2) (and strong (1))?
Based on DNA.
People still have to decide how much genetic difference makes two organisms members of different species. Collecting DNA used to be hard and long and expensive to analyse.
It’s getting cheaper now?
What is the evolutionary species model and why is it weak and strong?
Based on shared evolutionary relationships between species, members have shared evolution and are evolving together. Biologically sound!
Not easy to apply - not always clear evolutionary pathway for one organism.
Limitations of species models? (4)
- Finding evidence. Setting up breeding program is time-consuming ,expensive and may be useless.
- Plants of different closely related species interbreed to produce fertile hybrids - when should the hybrids be regarded as a separate species?
- Many organisms don’t reproduce sexually - reproductive models are irrelevant for bacteria fungi etc
- Fossil organisms can’t reproduce and we often don’t have accessible DNA of them, but they need classification.
What does DNA barcoding involve?
Looking at short genetic sequences from a part of the genome common to particular groups of organisms.
What is DNA profiling?
Process where non-coding areas of DNA are analysed to identify patterns.
How do lice show us anything about our ancestry?
Humans had head lice with chimpanzee louse ancestors, pubic lice with gorilla louse ancestors before the body lice evolved, meaning before we started wearing woven clothes.
What is molecular phylogeny?
Analysing structures of many different chemicals and DNA to identify relationships between groups of organisms.
What happens in gel electrophoresis for DNA identification?
Chemicals are placed in wells in a gel medium in a buffer, with known DNA/RNA fragments.
The big DNA molecules are cut into fragments by restriction endonuclease that cut DNA into fragments at specific sites - they’re added to a dyed gel which binds to the fragments and fluoresces under UV light.
A dye is added to the DNA too, and it moves slightly faster to show when to turn the machine off.
A current is passed through the apparatus, DNA fragments move towards positive anode, moving at different rates depending on mass and charge.
Why does the DNA fragment move towards the positive anode?
Because of the negative charge on the phosphate groups in the DNA
